A high magnetic permeability nanocrystalline soft magnetic alloy, strip, and preparation method and application thereof

Abstract

The present invention relates to a high permeability nanocrystalline soft magnetic alloy, a strip, a preparation method and an application thereof. The chemical formula of the high permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x wherein R is a rare earth element selected from at least one of La, Nd, and Y; M is a transition metal element selected from at least one of Zr and Hf; and a, b, c, d, h, f, j, k, and x are the atomic percentages of the corresponding components: 72≤a≤85, 2≤b≤5, 3≤c≤8, 1≤d≤2, 2≤h≤4, 2≤f≤4, 0.5≤j≤1, 0.5≤k≤2, and 0.5≤x≤2, and the sum of the atomic percentages of all components is 100. The nanocrystalline soft magnetic alloy of the present invention has high magnetic permeability and low loss, as well as excellent mechanical properties and thermal stability.

Description

Technical Field

[0001] The present invention belongs to the field of soft magnetic alloys and their preparation, and in particular relates to a high-permeability nanocrystalline soft magnetic alloy, a strip, and a preparation method and application thereof. Background Art

[0002] Soft magnetic materials are a class of materials that can be easily magnetized and demagnetized in an applied magnetic field. They possess high permeability, low coercivity, and low losses, making them key materials in modern power electronics. Common soft magnetic materials include silicon steel, ferrite, and amorphous alloys. However, these traditional materials face performance bottlenecks in high-frequency electromagnetic applications, making them difficult to meet the high efficiency, low loss, and high-frequency stability requirements of the next generation of power equipment.

[0003] As a traditional soft magnetic material, it has certain limitations. For example, silicon steel, a widely used soft magnetic material, has good low-frequency magnetic properties and high mechanical strength. However, silicon steel exhibits large eddy current losses and low magnetic permeability under high-frequency conditions, making it difficult to effectively use in high-frequency transformers and high-frequency motors.

[0004] Ferrite has high resistivity and low eddy current loss, but its saturation magnetic induction intensity is low and it cannot withstand high magnetic flux density. At the same time, it is very brittle and cannot meet the needs of certain high-strength mechanical applications.

[0005] Amorphous alloys, due to their amorphous structure, have low loss and high permeability, and excel in high-frequency applications. However, their poor thermal stability at high temperatures and lack of sufficient mechanical strength hinder their widespread application in certain high-intensity scenarios.

[0006] In contrast, nanocrystalline soft magnetic alloys offer application advantages in the aforementioned areas. First, nanocrystalline soft magnetic alloys are composite structural materials formed at the nanometer level by controlling the grain size based on amorphous alloys. While maintaining low loss and high magnetic permeability, they possess improved mechanical properties and thermal stability, making them ideal high-frequency soft magnetic materials. Second, existing nanocrystalline soft magnetic alloys mostly utilize a combination of elements such as iron, silicon, and boron. Their magnetic properties can be further enhanced by adding cobalt, nickel, and rare earth elements. Despite some research and applications, there is still considerable room for improvement in effectively refining grain size, improving thermal stability, and reducing losses.

[0007] Traditional nanocrystalline soft magnetic alloys often struggle to achieve both high permeability and low losses while maintaining thermal stability. They are prone to grain growth at high temperatures, leading to performance degradation. Furthermore, controlling eddy current and hysteresis losses is crucial for high-frequency applications. However, the grain uniformity and nanocrystallization of existing nanocrystalline soft magnetic alloys have yet to reach ideal levels, resulting in high losses at high frequencies.

[0008] To meet the high magnetic flux density requirements of complex power electronic devices, current nanocrystalline alloys still lack sufficient saturation magnetic induction, making it difficult to maintain good magnetic properties under high loads. Furthermore, existing preparation methods often face stability and consistency challenges in industrial production, making it difficult to ensure high performance in mass production. Summary of the Invention

[0009] The purpose of the present invention is to solve the problems of high loss, poor thermal stability and low saturation magnetic induction intensity of existing nanocrystalline soft magnetic materials at high frequencies.

[0010] The purpose of the present invention is to adopt the following technical solutions to achieve:

[0011] A high permeability nanocrystalline soft magnetic alloy, the chemical formula of the high permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x ;

[0012] Wherein, R is a rare earth element, selected from at least one of La, Nd and Y;

[0013] M is a transition metal element, selected from at least one of Zr and Hf;

[0014] a, b, c, d, h, f, j, k, and x are the atomic percentages of the corresponding components: 72≤a≤85, 2≤b≤5, 3≤c≤8, 1≤d≤2, 2≤h≤4, 2≤f≤4, 0.5≤j≤1, 0.5≤k≤2, 0.5≤x≤2, and the sum of the atomic percentages of all components is 100.

[0015] Preferably, the NbO is niobium oxide, which is introduced as a reactive substance during the smelting process and reacts with boron and silicon to form a composite phase.

[0016] During the initial smelting process, unlike previous alloys that used elemental niobium as a raw material, niobium oxide is introduced as a reactive species. It first reacts with boron to form niobium boride (NbB2), releasing heat and stabilizing the reaction environment. Niobium then reacts with silicon to form niobium silicide (NbSi2). This process effectively refines the grain structure and enhances inter-grain uniformity. Niobium also increases the magnetic permeability of the iron-based alloy while maintaining the alloy's low coercivity and high magnetic saturation strength.

[0017] Niobium silicide and niobium boride, formed through the composite reaction of niobium oxide with boron and silicon, effectively reduce hysteresis and eddy current losses. The niobium silicide and niobium boride composite phase effectively suppresses grain growth through a "pinning effect," ensuring that the grains remain within the nanoscale range. This refinement effect not only improves the soft magnetic properties but also enhances the mechanical strength and thermal stability of the alloy. Furthermore, the high melting point characteristics of niobium silicide and niobium boride impart thermal stability to the alloy in high-temperature environments. This means that during high-temperature annealing or actual application, the alloy's microstructure remains stable, preventing abnormal grain growth and ensuring the long-term stability of the soft magnetic properties in high-temperature environments.

[0018] Preferably, the high magnetic permeability nanocrystalline soft magnetic alloy is a high magnetic permeability nanocrystalline soft magnetic alloy strip.

[0019] Preferably, the resistivity of the soft magnetic alloy strip is 150-180 µΩ•cm; and / or

[0020] The saturation magnetic induction intensity of the soft magnetic alloy strip is 1.7 to 2.1 T; and / or

[0021] The high-frequency loss of the soft magnetic alloy strip is 10-20 W / kg at a frequency of 10 kHz and a magnetic flux density of 1 T.

[0022] The present invention also provides a method for preparing the high magnetic permeability nanocrystalline soft magnetic alloy strip, comprising the following steps:

[0023] According to the alloy composition of the high permeability nanocrystalline soft magnetic alloy, iron, cobalt, nickel, titanium, silicon, boron, rare earth elements, NbO and transition metal raw materials are accurately weighed, and the purity of all raw materials must be greater than 99%;

[0024] After mixing the raw materials, heating to 1800-2000° C. under inert gas protection, and melting for 5-10 minutes to obtain a molten alloy;

[0025] Rapidly cooling the molten alloy through a centrifugal casting process to obtain alloy flakes;

[0026] The alloy flakes are cleaned and dried, and the dried alloy flakes are ball-milled to obtain refined particles;

[0027] The refined particles are placed in a mold, and hot-pressed at a temperature of 600 to 900° C., a molding pressure of 400 to 800 MPa, and a molding time of 30 to 60 minutes to obtain a block material;

[0028] The block material is placed in a hot rolling mill and rolled in multiple passes at a temperature of 500 to 700° C. to obtain a strip with a thickness of 10 to 14 μm;

[0029] Continuous annealing: performing continuous annealing treatment on the strip at 250-560° C. for 2-4 hours to obtain the high magnetic permeability nanocrystalline soft magnetic alloy strip.

[0030] Preferably, the inert gas is argon with a purity greater than 99.99%. In plasma smelting, the use of high-purity argon can prevent impurities from contaminating the molten metal, and strict control of the smelting temperature and time can prevent element loss and incomplete reaction.

[0031] Preferably, the rapidly cooling the molten alloy through a centrifugal casting process specifically includes:

[0032] The molten alloy is rapidly cooled under vacuum conditions by a centrifugal casting process at a cooling rate greater than 10 4 K / s.

[0033] The rapid centrifugal cooling process is carried out under vacuum conditions to avoid oxidation of the alloy surface while ensuring the stability of the centrifugal speed and cooling rate; the cooling rate must be controlled at more than 10 4 K / s to ensure that the alloy solidifies rapidly to form flake-like materials and realizes the initial transition between amorphous and nanocrystalline in microstructure.

[0034] Preferably, the drying specifically includes: performing the drying in a vacuum drying oven at a drying temperature of 50-100°C.

[0035] Preferably, in the ball milling treatment, the ball milling medium is a cemented carbide ball, and the ball milling time is 1 to 2 hours.

[0036] The ball milling medium is a cemented carbide ball, which can reduce the contamination of the material during the ball milling process.

[0037] Preferably, in the hot pressing process, the molding pressure is 600-800 MPa, and the molding time is 45-60 minutes.

[0038] Preferably, the number of rolling passes is no less than 5 times.

[0039] Preferably, the continuous annealing treatment adopts a graded annealing process, with the first stage temperature being 200~300℃; the second stage temperature being 300~400℃; the third stage temperature being 400~500℃; and the fourth stage temperature being 520~560℃; the treatment time of each stage does not exceed 1 hour, and the total continuous annealing time does not exceed 4 hours.

[0040] Temperature control is key during the continuous annealing process, and graded treatment effectively stabilizes the nanocrystalline structure and improves magnetic properties. The annealing process also helps homogenize the nanocrystalline phase, enhancing magnetic permeability and soft magnetic properties. Each stage of treatment lasts no more than one hour, and the total continuous annealing time does not exceed four hours, which prevents grain growth within this timeframe.

[0041] Preferably, the method further comprises performing surface treatment on the high permeability nanocrystalline soft magnetic alloy strip using electrolytic polishing technology.

[0042] The present invention also provides the use of the high-permeability nanocrystalline soft magnetic alloy strip prepared by the preparation method in high-frequency transformers, inductors and stators and rotors of motors.

[0043] In practical applications, the high magnetic permeability nanocrystalline soft magnetic alloy strip can also be cut and rolled according to application requirements.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The high permeability nanocrystalline soft magnetic alloy provided by the present invention has a chemical formula of Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x; wherein R is a rare earth element selected from at least one of La, Nd and Y; M is a transition metal element selected from at least one of Zr and Hf; the a, b, c, d, h, f, j, k, and x are the atomic percentages of the corresponding components: 72≤a≤85, 2≤b≤5, 3≤c≤8, 1≤d≤2, 2≤h≤4, 2≤f≤4, 0.5≤j≤1, 0.5≤k≤2, 0.5≤x≤2, and the sum of the atomic percentages of all components is 100. The present invention optimizes the magnetic domain structure and reduces magnetic losses through the combined action of iron, cobalt, nickel, silicon, and rare earth elements in a rationally proportioned manner. The alloy's magnetic permeability is significantly improved, particularly in high-frequency applications, where it significantly enhances magnetic response. The addition of transition metals (such as zirconium and hafnium) improves the alloy's structural stability at high temperatures. These elements react with titanium, boron, and rare earth elements to form a variety of nanoscale composite phases, significantly enhancing the alloy's oxidation resistance and magnetic properties at high temperatures. The present invention utilizes the synergistic effects of multiple elements, including iron, cobalt, nickel, titanium, silicon, boron, rare earth elements, niobium oxide, and transition metals. This diversified design not only results in high magnetic permeability and low losses, but also optimizes mechanical properties and thermal stability, particularly high tensile strength and ductility. In summary, the nanocrystalline soft magnetic alloy of the present invention exhibits significant electromagnetic properties, excellent mechanical properties, and thermal stability, along with good process stability and cost-effectiveness. This makes the alloy excellent in high-frequency electromagnetic applications, with broad application potential and market value.

[0046] The method for preparing a high-permeability nanocrystalline soft magnetic alloy provided in this application utilizes processes such as plasma melting, rapid cooling, ball milling, hot pressing, hot rolling, and continuous annealing to form a strip with a uniform nanocrystalline structure. Rapid cooling and a rational annealing process promote the formation and stabilization of the nanocrystalline phase, effectively improving the alloy's overall performance. Furthermore, this preparation method is stable and suitable for mass production, ensuring product consistency and quality stability.

[0047] The high-permeability nanocrystalline soft magnetic alloy provided by the present invention is suitable for use in stators and rotors of high-frequency transformers, inductors, and electric motors. Due to its high permeability, low loss, and high thermal stability, it can significantly improve the efficiency and stability of these devices under high-frequency operating conditions. DETAILED DESCRIPTION

[0048] The following examples clearly and completely describe the technical solutions of the present invention. Obviously, the described examples are only some of the embodiments of the present invention and cannot be considered as all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] A high permeability nanocrystalline soft magnetic alloy, the chemical formula of the high permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x ;

[0050] Wherein, R is a rare earth element, selected from at least one of La, Nd and Y;

[0051] M is a transition metal element, selected from at least one of Zr and Hf;

[0052] The a, b, c, d, h, f, j, k, and x are the atomic percentages of the corresponding components: 72≤a≤85, 2≤b≤5, 3≤c≤8, 1≤d≤2, 2≤h≤4, 2≤f≤4, 0.5≤j≤1, 0.5≤k≤2, 0.5≤x≤2, and the sum of the atomic percentages of all components is 100.

[0053] The NbO is niobium oxide, which is introduced as a reactive substance during the smelting process and reacts with boron and silicon to form a composite phase.

[0054] In the present invention, except for NbO which is niobium oxide, the raw materials of the above chemical formula are all simple substances of the respective elements, and all have high purity: greater than 99%.

[0055] The role of each element in the alloy of the present invention is described below:

[0056] Iron (Fe) is the main component of iron-based nanocrystalline soft magnetic alloys, providing high magnetic permeability and magnetic saturation strength, and is the core foundation of soft magnetic properties. When the atomic percentage of Fe is 72≤a≤85, as the base metal, the interaction between iron and other elements can form a stable alloy grain structure and a distribution of nanocrystalline phases. At the same time, the amorphous / nanocrystalline composite structure formed ensures relatively high magnetic permeability and magnetic saturation strength. When the atomic percentage of Fe is less than 72, the interaction between iron and other elements becomes weak, and the strength of the formed alloy is insufficient, which affects subsequent applications.

[0057] The role of cobalt (Co) is to improve the magnetic saturation strength and magnetic permeability, especially in high-frequency applications. In addition, the cobalt element can provide better thermal stability and reduce the performance degradation of the material at high temperatures. When the atomic percentage of Co is 2≤b≤5, it is easier to form a eutectic phase with iron, thereby improving the magnetic properties of the material, and at the same time promoting the formation of nanocrystals during the smelting process. And when the atomic percentage of Co is within the above range, it is easy to form a complex phase with silicon, titanium and rare earth elements, further refining the grain structure. However, when the atomic percentage of Co is greater than 5, it will cause magnetic loss and coercive force to increase, and the soft magnetic properties will deteriorate.

[0058] The role of nickel (Ni) is to increase the corrosion resistance and machinability of the alloy, while also helping to improve magnetic permeability; in high-frequency magnetic fields, nickel can reduce hysteresis loss. When the atomic percentage of Ni is 3≤c≤8, it is easier to form a solid solution with iron and cobalt, which helps stabilize the nanocrystalline phase. When the atomic percentage of Ni is within the above range, nickel further promotes the uniform distribution of boron during the smelting process, which helps the formation of nanocrystals. However, when the atomic percentage of Ni is greater than 8, it will cause eddy current loss and coercive force to increase, and the soft magnetic properties will deteriorate.

[0059] Titanium (Ti) acts as a grain refiner, inhibiting grain growth and helping to maintain the uniformity of the nanocrystalline structure. It enhances the alloy's mechanical properties, giving the strip greater tensile strength and wear resistance. When the atomic percentage of Ti is 1 ≤ d ≤ 2, titanium more easily forms titanium boride or titanium silicide with boron and silicon during the smelting process, contributing to the uniform distribution of the nanocrystalline phase and grain refinement. At the same time, within this range, the structural stability of the alloy can be improved by interacting with rare earth elements, especially during high-temperature annealing. When the atomic percentage of Ni is greater than 2, the saturation magnetic induction decreases.

[0060] Silicon (Si) increases the resistivity of the alloy, helping to reduce eddy current losses; it also promotes the formation of an amorphous phase, further enhancing the alloy's soft magnetic properties. When the atomic percentage of Si is 2 ≤ h ≤ 4, silicon reacts more easily with niobium oxide during the smelting process to form niobium silicide, which helps refine the grain structure. At the same time, silicon dissolves with iron and nickel, helping to improve the uniformity of the nanocrystalline phase distribution and maintain structural stability during subsequent heat treatment. However, when the atomic percentage of Si is greater than 4, the saturation magnetic induction decreases.

[0061] Boron (B) is a typical nanocrystal-forming element, promoting the rapid formation of an amorphous phase. It improves the alloy's high-frequency magnetic permeability while reducing hysteresis losses. When the atomic percentage of B is 2 ≤ f ≤ 4, it reacts with titanium, rare earth elements, and niobium oxides to form titanium and niobium borides, further refining the grains and improving the material's high-temperature resistance. Furthermore, during melting and annealing, the interaction between boron and rare earth elements helps reduce impurities and enhance magnetic properties. When the atomic percentage of B exceeds 4, the saturation magnetic induction decreases.

[0062] Rare earth elements (lanthanum La, neodymium Nd, yttrium Y) help improve the high magnetic permeability and oxidation resistance of nanocrystalline soft magnetic alloys. The addition of rare earth elements to the alloy can significantly reduce the impurity content and improve the magnetic properties of the alloy. When the atomic percentage of rare earth elements is 0.5≤j≤1, the rare earth elements react with titanium and boron during the smelting process to form composite phases. These composite phases can further refine the grains and promote the stabilization of amorphous and nanocrystalline phases. At the same time, they can inhibit grain growth during high-temperature annealing and maintain the uniformity of the nanocrystalline structure. When the atomic percentage of rare earth elements is greater than 1, the saturation magnetic induction will be reduced and the magnetic properties will deteriorate.

[0063] Niobium oxide (NbO) is introduced as a reactive species, reacting with boron and silicon during the smelting process to form niobium silicide and niobium boride. When the atomic percentage of niobium oxide is 0.5 ≤ x ≤ 2, these composite phases help improve magnetic permeability, refine grain size, and enhance the thermal stability of the material. The chain reaction between niobium oxide, silicon, and boron promotes the formation of complex nanocomposite phases, which significantly enhance the soft magnetic properties of the alloy. Furthermore, within this atomic percentage range, niobium oxide can also regulate the grain size and distribution of the alloy, enhancing the material's high-temperature resistance. When the atomic percentage of niobium oxide exceeds 2, the saturation magnetic induction decreases, deteriorating the magnetic properties. The atomic percentage of niobium oxide is preferably 0.6 ≤ x ≤ 1.8, and more preferably 0.75 ≤ x ≤ 1.5.

[0064] Regarding the mechanism of improving material properties by forming composites with niobium oxides:

[0065] Reaction of niobium oxide with silicon:

[0066] During the melting process, niobium oxide reacts chemically with silicon to form niobium silicide (NbSi2). This compound is a high-melting-point, hard compound distributed in the melt as nanoparticles. Furthermore, the formation of niobium silicide helps inhibit grain growth by creating a barrier effect at grain boundaries, preventing further grain expansion. Furthermore, nanoscale niobium silicide particles promote the formation and stabilization of amorphous and nanocrystalline phases in the alloy matrix.

[0067] Reaction of niobium oxide with boron:

[0068] Niobium oxide can also react with boron at high temperatures to form niobium borides (such as NbB2). Niobium borides are hard phases that act as effective grain refiners, further reducing grain size and ensuring uniform distribution within the material matrix. Furthermore, the formation of niobium borides helps inhibit grain growth and improve the material's magnetic permeability. The nanostructure of this composite phase effectively optimizes the magnetic domain structure and enhances the material's soft magnetic properties.

[0069] The role of grain refinement:

[0070] The resulting nanoscale distribution of niobium silicide and niobium boride inhibits grain growth in the iron-based alloy through a pinning effect at the grain boundaries. This refinement not only improves the alloy's strength and hardness, but also enhances its soft magnetic properties. Furthermore, the refinement and homogenization of the grains reduces the resistance to magnetic domain wall movement, improving magnetic permeability and magnetic saturation strength.

[0071] Effect of improving magnetic permeability:

[0072] The presence of niobium silicide and niobium boride improves the uniformity and consistency of the magnetic domains within the material. Because these nanoscale composite phases form a continuous distribution within the alloy matrix, they help reduce hysteresis losses, thereby increasing magnetic permeability. Furthermore, these composite phases in the microstructure reduce the energy barrier at the grain boundaries, facilitating the movement of magnetic domain walls and significantly improving the alloy's magnetic properties.

[0073] Enhanced thermal stability:

[0074] The presence of niobium silicide and niobium boride increases the alloy's high-temperature stability. Due to their high melting points and excellent thermal stability, these composite phases effectively inhibit abnormal matrix grain growth at high temperatures, thereby maintaining the alloy's stable microstructure. This means that during high-temperature annealing or actual application, the alloy's soft magnetic properties can be maintained for extended periods, avoiding performance degradation due to grain growth.

[0075] Furthermore, in the nanocrystalline soft magnetic alloy of the present invention, transition metals (zirconium (Zr) and hafnium (Hf)) act as additional grain refiners, further refining the alloy's grains during the smelting process, improving its structural stability and magnetic permeability. These metals react with titanium, boron, and rare earth elements to form multiple composite phases, all of which help maintain the material's nanocrystalline structure and stability.

[0076] In summary, the aforementioned elements, through their interactions and the formation of composite phases, collectively refine the grains, enhance magnetic permeability, reduce losses, and improve high-temperature resistance and thermal stability. The combined effects of these elements and their interactions ensure that iron-based nanocrystalline soft magnetic alloys possess high magnetic permeability, low losses, high magnetic saturation strength, and good thermal stability. By optimizing the proper proportions of the elements and their interactions, a stable nanocrystalline phase can be formed in the microstructure, further enhancing the material's soft magnetic properties.

[0077] Furthermore, the resistivity of the alloy is 150-180 µΩ•cm, the saturation magnetic induction intensity is 1.7-2.1 T, and the high-frequency loss is 10-20 W / kg at a frequency of 10 kHz and a magnetic flux density of 1 T.

[0078] The alloy of the present invention can be used in high-frequency transformers, inductors, and stators and rotors of electric motors.

[0079] Example 1

[0080] This embodiment provides a nanocrystalline soft magnetic alloy, the chemical formula of the nanocrystalline soft magnetic alloy is: Fe 76 Co5Ni7Ti1Si3B4R1M2(NbO)1; wherein R is La; M is Zr; and NbO is niobium oxide.

[0081] This embodiment also provides a nanocrystalline soft magnetic alloy strip, and a method for preparing the strip includes the following steps:

[0082] 1) Raw material configuration

[0083] According to the above elemental chemical composition formula, iron, cobalt, nickel, titanium, silicon, boron, La, niobium oxide and Zr with a purity greater than 99% are weighed;

[0084] And accurately weigh according to the preset ratio of the above chemical formula;

[0085] Ensure all raw materials are evenly mixed and placed in a dry environment to prevent the influence of impurities and moisture.

[0086] 2) Plasma melting

[0087] Place all raw materials into a plasma melting furnace and heat them in an argon atmosphere (argon purity ≥ 99.99%);

[0088] The melting temperature was set at 1850°C and the melting time was 610 minutes to ensure that the alloy raw materials were completely melted and fully mixed.

[0089] 3) Rapid centrifugal cooling

[0090] The molten alloy is thrown out through a centrifugal casting device at a speed of 35m / s, and then4 K / s for rapid cooling to form alloy flakes.

[0091] 4) Cleaning and drying

[0092] The alloy flakes formed by centrifugal casting were immersed in deionized water for cleaning, and then placed in a vacuum drying furnace for drying at a drying temperature controlled at 60° C. to remove surface moisture.

[0093] 5) Ball milling

[0094] The dried alloy flakes were placed in a high-energy ball mill using carbide balls as the milling medium for 1 hour to further refine the particles and improve uniformity.

[0095] 6) Hot pressing

[0096] The ball-milled particles were loaded into a mold and hot-pressed at 650°C. The pressing force was set at 700 MPa and maintained for 50 minutes to ensure the close bonding and density of the particles and form a bulk material.

[0097] 7) Hot rolling

[0098] The hot-pressed bulk material is placed in a hot rolling mill and rolled into strips with a thickness of 10 microns at a temperature of 600°C to achieve an ideal nanocrystalline structure.

[0099] 8) Continuous annealing

[0100] The rolled strips are placed in a continuous annealing furnace and subjected to a graded annealing process to obtain annealed strips. The graded annealing temperatures are 250°C, 350°C, 450°C, and 550°C, respectively, and each stage takes 1 hour, for a total annealing time of 4 hours.

[0101] 9) Surface treatment and molding

[0102] The annealed strip is subjected to electrolytic polishing and forming, thereby obtaining a nanocrystalline soft magnetic alloy strip.

[0103] Example 2-12

[0104] The alloy composition and percentage content of Examples 2 to 12 are shown in Table 1. The preparation method is basically the same as that of Example 1, and the specific process parameters are different as shown in Table 2.

[0105] Table 1 Compositions of Examples 1 to 12

[0106]

[0107] Table 2 Process conditions used in the preparation methods of Examples 1 to 12

[0108]

[0109] Comparative Examples 1-3

[0110] Three comparative products on the market were used for relevant comparison. The compositions of the comparative products are shown in Table 3.

[0111] Table 3 Compositions of Comparative Examples 1 to 3

[0112]

[0113] Test Case

[0114] The high permeability nanocrystalline soft magnetic alloy strips prepared in Examples 1 and 2 were subjected to performance tests and compared with three comparative products on the market (Comparative Examples 1 and 2). The test results are shown in Table 4.

[0115] Table 4 Performance test results of Examples 1 to 12 and Comparative Examples 1 to 3

[0116]

[0117] Methods and equipment used to test the performance of the above products:

[0118] 1. Resistivity test

[0119] Test method: The resistivity of the alloy strip is measured using the four-probe method.

[0120] Test conditions: carried out at room temperature, sample size is 20 mm × 5 mm × 0.013 mm.

[0121] Result analysis:

[0122] As shown in Tables 1-4, in Examples 1-12, when the component element contents and process conditions were within the ranges of the present invention, the resulting nanocrystalline soft magnetic alloy strips exhibited resistivities ranging from 160-172 μΩ·cm. Compared to the comparative examples, where the component contents and process conditions were outside the ranges of the present invention, these resistivities were higher than those of the existing comparative examples 1-3 (150-155 μΩ·cm). Therefore, the products of the present invention meet the target market requirements (160-180 μΩ·cm). This indicates that the alloy strips of the present invention exhibit higher resistivities, which translates to lower eddy current losses at high frequencies.

[0123] 2. Saturation magnetic induction intensity test

[0124] Test method: The saturation magnetic induction intensity is measured using a vibrating sample magnetometer (VSM) under an external magnetic field.

[0125] Test conditions: Magnetic field range of 0-2 T, sample size 10 mm × 10 mm × 0.013 mm.

[0126] Result analysis:

[0127] As can be seen from Tables 1-4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and the process conditions are within the scope of the present invention, the saturation magnetic induction intensity of the obtained nanocrystalline soft magnetic alloy strip is between 1.7 and 1.85 T, which is significantly higher than 1.52-1.6 T of the comparative example whose indicators are not within the scope of the present invention.

[0128] This shows that the nanocrystalline soft magnetic alloy of the present invention has higher magnetic saturation performance and is more suitable for high magnetic flux density application scenarios.

[0129] 3. Coercivity test

[0130] Test method: The coercivity of the alloy is evaluated using the BH curve method.

[0131] Test conditions: Measured at 25°C and a magnetic field of 0-100 A / m.

[0132] Result analysis:

[0133] As can be seen from Tables 1-4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and the process conditions are within the scope of the present invention, the coercive force of the obtained nanocrystalline soft magnetic alloy strip is between 2.1 and 3.0 A / m, which is much lower than the 3.5-3.8 A / m of the comparative example not within the scope of the present invention.

[0134] As those skilled in the art know, a lower coercive force indicates better magnetic properties, and therefore materials with lower coercive force are more suitable for applications in high-frequency transformers and inductors.

[0135] 4. High frequency loss test

[0136] Test method: Use an iron loss analyzer to test at a frequency of 10 kHz and a magnetic flux density of 1 T.

[0137] Test conditions: Sample size is 30 mm × 5 mm × 0.013 mm.

[0138] Result analysis:

[0139] As can be seen from Tables 1-4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and the process conditions are within the scope of the present invention, the high-frequency loss of the obtained nanocrystalline soft magnetic alloy strip is 14 to 18 W / kg. Only Example 1 has a high-frequency loss of 18, and the others are all lower than 18. That is to say, Examples 2 to 12 are generally lower than 18-19 W / kg of the comparative example, which is in line with the target range (10-20 W / kg).

[0140] Although the high-frequency losses of the embodiment and the comparative example are both within the range of industry targets, lower high-frequency losses mean that the material performs better under high-frequency conditions, can reduce energy losses in transformers and inductors, reduce economic costs, and enhance its application value in related industries.

[0141] 5. Magnetic permeability test

[0142] Test method: Use an AC magnetic permeability meter to measure at 1 kHz and 1 T.

[0143] Test conditions: Sample size: 10 mm × 10 mm × 0.013 mm.

[0144] Result analysis:

[0145] It can be seen from Tables 1-4 that in Examples 1 to 12, when the content of each component element is within the scope of the present invention and the process conditions are within the scope of the present invention, the magnetic permeability of the obtained nanocrystalline soft magnetic alloy strip is between 55,000 and 64,000, which is significantly higher than 48,000 to 52,000 of the comparative examples not within the scope of the present invention.

[0146] Since higher magnetic permeability indicates that the material has excellent magnetic response characteristics at high frequencies, the material of the present invention is more suitable for applications in high-frequency transformers and motors.

[0147] 6.Tensile strength and elongation test

[0148] Test method: Use a material testing machine to test in accordance with GB / T228.1-2010 standard.

[0149] Test conditions: sample size is 10 mm × 10 mm × 0.013 mm, and the tensile rate is 10 mm / min.

[0150] Result analysis:

[0151] As can be seen from Tables 1-4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and the process conditions are within the scope of the present invention, the tensile strength of the obtained nanocrystalline soft magnetic alloy strip is 1200-1400 MPa, and the elongation is between 5-6%, which are both higher than the tensile strength (1050-1100 MPa) and elongation (3.5-4%) of the comparative example.

[0152] This means that Examples 1 to 12 have high mechanical strength and ductility while maintaining excellent magnetic properties.

[0153] In summary:

[0154] From the perspective of electromagnetic performance, the electromagnetic performance of Examples 1 to 12 is significantly higher than that of existing products, including higher saturation magnetic induction intensity, lower coercive force and higher magnetic permeability, indicating that they have greater application potential in high-frequency transformers, inductors and motors.

[0155] From the perspective of mechanical properties, the improvement in tensile strength and elongation of the alloy of the present invention proves that the embodiment maintains good mechanical properties while having high magnetic permeability and low loss.

[0156] From the perspective of process stability, under the same process conditions, the embodiment shows better comprehensive performance, which proves the rationality of the process scheme and the superiority of the material design.

[0157] In addition, the strips of the embodiments are suitable for high-frequency transformers, inductors, and stators and rotors of electric motors, and can effectively reduce losses and improve equipment efficiency and stability in high-frequency applications.

[0158] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high permeability nanocrystalline soft magnetic alloy, characterized in that: The chemical formula of the high permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x ; Wherein, R is a rare earth element, selected from at least one of La, Nd and Y; M is a transition metal element, selected from at least one of Zr and Hf; a, b, c, d, h, f, j, k, and x are the atomic percentages of the corresponding components: 72≤a≤85, 2≤b≤5, 3≤c≤8, 1≤d≤2, 2≤h≤4, 2≤f≤4, 0.5≤j≤1, 0.5≤k≤2, 0.5≤x≤2, and the sum of the atomic percentages of all components is 100.

2. The high permeability nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The NbO is niobium oxide, which is introduced as a reactive substance during the smelting process and reacts with boron and silicon to form a composite phase.

3. The high permeability nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The resistivity of the soft magnetic alloy is 150-180 µΩ•cm; and / or The saturation magnetic induction intensity of the soft magnetic alloy is 1.7 to 2.1 T; and / or The high-frequency loss of the soft magnetic alloy is 10-20 W / kg at a frequency of 10 kHz and a magnetic flux density of 1 T.

4. The high permeability nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The nanocrystalline soft magnetic alloy is a high magnetic permeability nanocrystalline soft magnetic alloy strip.

5. A method for preparing a high permeability nanocrystalline soft magnetic alloy strip, characterized in that: The following steps are involved: According to the alloy composition of the high permeability nanocrystalline soft magnetic alloy according to any one of claims 1 to 3, iron, cobalt, nickel, titanium, silicon, boron, rare earth elements, niobium oxide and transition metal raw materials are accurately weighed, and the purity of all raw materials must be greater than 99%; After mixing the raw materials, heating to 1800-2000° C. under inert gas protection, and melting for 5-10 minutes to obtain a molten alloy; Rapidly cooling the molten alloy through a centrifugal casting process to obtain alloy flakes; The alloy flakes are cleaned and dried, and the dried alloy flakes are ball-milled to obtain refined particles; The refined particles are placed in a mold and hot-pressed at a temperature of 600 to 900° C., a molding pressure of 400 to 800 MPa, and a molding time of 30 to 60 minutes to obtain a block material; The block material is placed in a hot rolling mill and rolled in multiple passes at a temperature of 500 to 700° C. to obtain a strip with a thickness of 10 to 14 μm; The strip is subjected to continuous annealing treatment at 250-560° C. for 2-4 hours to obtain the high magnetic permeability nanocrystalline soft magnetic alloy strip.

6. The preparation method according to claim 5, characterized in that The inert gas is argon with a purity greater than 99.99%.

7. The preparation method according to claim 5, characterized in that The rapidly cooling the molten alloy through the centrifugal casting process specifically includes: The molten alloy is rapidly cooled under vacuum conditions by a centrifugal casting process at a cooling rate greater than 10 4 K / s.

8. The preparation method according to claim 5, characterized in that The drying specifically includes: performing the drying in a vacuum drying oven at a drying temperature of 50-100°C.

9. The preparation method according to claim 5, characterized in that In the ball milling process, the ball milling medium is a cemented carbide ball, and the ball milling time is 1 to 2 hours.

10. The preparation method according to claim 5, characterized in that In the hot pressing process, the molding pressure is 600-800 MPa and the molding time is 45-60 minutes.

11. The preparation method according to claim 5, characterized in that The rolling passes shall be no less than 5 times.

12. The preparation method according to claim 5, characterized in that The continuous annealing treatment adopts a graded annealing process, with the first stage temperature being 200-300°C; the second stage temperature being 300-400°C; the third stage temperature being 400-500°C; and the fourth stage temperature being 520-560°C; the treatment time of each stage not exceeding 1 hour, and the total continuous annealing time not exceeding 4 hours.

13. The preparation method according to claim 5, characterized in that The method further includes performing surface treatment on the high magnetic permeability nanocrystalline soft magnetic alloy strip using an electrolytic polishing technology.

14. Use of a high permeability nanocrystalline soft magnetic alloy strip prepared by the preparation method according to any one of claims 5 to 13 in high-frequency transformers, inductors, and stators and rotors of electric motors.

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